Summarized Consolidating Financial Data - Consolidating Income Statements (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 24, 2016	Jun. 26, 2015	Jun. 24, 2016	Jun. 26, 2015
Consolidated Income Statement
Revenue	$ 2,704	$ 3,064	$ 5,322	$ 6,091
Expense	1,864	2,047	3,778	4,231
Operating Income	840	1,017	1,544	1,860
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(141)	(134)	(284)	(268)
Other Income / (Expense) - Net	8	4	15	6
Earnings Before Income Taxes	707	887	1,275	1,598
Income Tax Benefit / (Expense)	(262)	(334)	(474)	(603)
Net Earnings	445	553	801	995
Total Comprehensive Earnings	454	565	817	1,005
CSX Corporation
Consolidated Income Statement
Revenue	0	0	0	0
Expense	(67)	(146)	(139)	(294)
Operating Income	67	146	139	294
Equity in Earnings of Subsidiaries	493	546	894	986
Interest (Expense) / Benefit	(141)	(132)	(284)	(265)
Other Income / (Expense) - Net	0	(2)	1	(3)
Earnings Before Income Taxes	419	558	750	1,012
Income Tax Benefit / (Expense)	26	(5)	51	(17)
Net Earnings	445	553	801	995
Total Comprehensive Earnings	454	565	817	1,005
CSX Transportation
Consolidated Income Statement
Revenue	2,685	3,045	5,283	6,052
Expense	1,961	2,239	4,025	4,583
Operating Income	724	806	1,258	1,469
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(10)	(9)	(20)	(16)
Other Income / (Expense) - Net	8	7	15	13
Earnings Before Income Taxes	722	804	1,253	1,466
Income Tax Benefit / (Expense)	(269)	(305)	(467)	(551)
Net Earnings	453	499	786	915
Total Comprehensive Earnings	454	499	786	912
Eliminations and Other
Consolidated Income Statement
Revenue	19	19	39	39
Expense	(30)	(46)	(108)	(58)
Operating Income	49	65	147	97
Equity in Earnings of Subsidiaries	(493)	(546)	(894)	(986)
Interest (Expense) / Benefit	10	7	20	13
Other Income / (Expense) - Net	0	(1)	(1)	(4)
Earnings Before Income Taxes	(434)	(475)	(728)	(880)
Income Tax Benefit / (Expense)	(19)	(24)	(58)	(35)
Net Earnings	(453)	(499)	(786)	(915)
Total Comprehensive Earnings	$ (454)	$ (499)	$ (786)	$ (912)